Real-Time Monitoring of Glycemic Starch Using Biosynthesized Gold Nanoparticle–Amylase Composites

Abstract

The enzymatic biosynthesis of gold nanoparticles (AuNPs) is achieved by the in situ reduction of gold ions with the help of the α-amylase enzyme as a reducing cum linking agent. Subsequently, the as-synthesized AuNP−α-amylase nanocomposite shows a host of exciting enzymatic activities toward the rapid degradation of starch when the size is varied from ∼10 to ∼40 nm. The nanocomposite has a superior activity as compared to free α-amylase for starch degradation. Importantly, the AuNP−α-amylase nanocomposite is utilized for the classification of rapidly (RDS) and slowly digestible starch (SDS) alongside resistant starch (RS) with the help of a standard 5 min starch hydrolysis experiment, based on the amount of maltose produced. Consequently, a point-of-care device has been developed for the real-time determination of the glycemic index (GI) of different food sources wherein the concentration of maltose produced after hydrolysis of starch by the nanocomposite is determined by chronoamperometry using screen-printed electrodes. In this device, maltose reduces [Fe­(CN)6]3– to [Fe­(CN)6]4– to generate a current signal proportional to the amount of maltose produced after starch hydrolysis by the nanocomposite. Concisely, the study demonstrates a simple, fast, reliable, portable, and inexpensive point-of-care testing (POCT) prototype for real-time determination of the GI of food sources.

Self-Organized Synthesis of Nanoserpent Clusters on Templated Starch for Sensitive Detection of Pancreatic α-Amylase

“…The free soluble starch and the bound soluble starch on AuNS hydrolysis were performed by the α-amylase of the same concentration. The free starch concentration equivalent to the AuNS-bound starch concentration is determined by the Raman spectrum . The detailed protocol has been discussed in Section V of the Supporting Information.…”

“…The free starch concentration equivalent to the AuNS-bound starch concentration is determined by the Raman spectrum. 66 The detailed protocol has been discussed in Section V of the Supporting Information. Figure 6A shows the variation of In([C ∞ −C t ]/ C ∞ ) with time for soluble starch and AuNS, where C ∞ is the amount of maltose produced at t = ∞ (i.e., when the absorbance no longer increases and reaches saturation).…”